Marking tool for screw machines



Sept. 11, 1962 w. R. KING 3,053,172

MARKING TOOL FOR SCREW MACHINES Filed April 21. 1960 v w n m' w w i, I, I. '0' 1M I t"! l5 1 I7 A n "l h- Fig. I. T

INVENTOR.

William R. King BY M, M m

" ATTQQNEYS United States Patent Filed Apr. 21, 1960, Ser. No. 23,685 3 Claims. ((31.101-7) This invention is for a tool for use in screw machines or like metal working machines, and is for a tool for impressing a marking, such as a code, identification, or other indicia on each work piece produced by the machine when the tool is used.

In a screw machine for example, a length of metal stock is advanced the necessary increment to form an article. Relative rotation is effected between the stock and a number of tools mounted in tool holders on cross slides constituting part of the machine. These tools are moved in a predetermined sequence into engagement with the work piece, the final tool in the series usually cutting off the finished piece, whereupon another length of stock is advanced and the cycle repeated.

According to the present invention a marking tool is provided that may be used in such a machine for engaging the work piece and impressing some desired marking therein. The tool includes a marking wheel having raised characters of some kind thereon. The wheel is pressed against the revolving work piece and is rotated by engagement therewith to bring the marking characters against the metal of the work piece and so impress a mark into the metal.

The present invention has for a principal object to provide a tool for this purpose.

It is important that the marking wheel rotate sulficiently to make a single impression of the characters on the marking wheel and then stop, and a further object of the present invention is to provide a machine in which the rotation of the marking wheel is less than, or does not exceed 360.

Also, after the impression has been made in a work piece, the marking wheel should return to its starting position, but only after the tool is clear of the work piece. A further object of this invention is to provide a tool in which the reverse rotation of the wheel to its initial poistion is effected through a spring and wherein the means to limit the rotation of the marking wheel by engagement with the work piece is a friction brake which holds the marking wheel against reverse rotation under the action of the spring until the tool has been moved clear of the work piece.

A further object of the invention is to provide a tool of this character where an operating lever is provided to release the brake when the tool is withdrawn from workcontacting position.

These and other objects and advantages are secured by my invention which may be more fully understood by reference to the accompanying drawings, in which:

FIG. 1 is a top plan view of a tool embodying my in vention;

FIG. 2 is a side elevation thereof;

FIG. 3 is a section in the plane of line IIIIII of FIG. 1, part of the shank being broken away; and

FIG. 4 is an end elevation.

In the drawings, 2 dsignates the shank of the tool which is designed to be received in a tool holder of a screw machine, although in some cases an adapter may be required. At the outer end of the shank is a bifurcated head portion 3 which is oifset to one side of the longitudinal axis of the shank, and which has parallel spaced extensions 4 and 5. These extensions provide bearing supports for a rotatable marking wheel assembly designated generally as 6, and comprising a shaft 7 that has a grooved wheel 8 at one end. Alongside the wheel 8 and fixed with reference to the shaft and grooved wheel is an eccentric cam 9. Alongside the cam 9 is a bearing portion 10 that is rotatably fitted into an opening in the extension 5. The shaft 7 extends across the space between the extensions 4 and 5, and a rotatable marking die or wheel 11 is removably carried on the shaft between the two extensions. It is provided on its periphery with embossed indicia or marking elements at 12. The shaft 7 passes through a bushing in the extension 4, and a cap 13 secured onto the end of the shaft holds the shaft assembly against endwise movement. To replace the marking wheel or die 11, the screw 14 may be removed to remove the cap 13, whereupon the shaft assem: bly may be slid endwise a distance sufficient to permit removal of one marking wheel and the substitution of another.

On one side face of the head portion 5 of the tool and comprising part of the head is a block 15. It provides a guideway for a slidable brake member 16, the end of which extends forwardly toward the periphery of the cam 9. There is a spring 17 in the block 15 hearing against the other end of the brake member. There is an adjusting rod 16a secured to the block, and which projects beyond the rear end of the block. It carries an adjusting nut 18 that limits the forward thrust of the brake 16 under the action of the spring 17 so as to predetermine that point in the rotation of the cam 9 where it will contact the end of the brake and thereby vary the pressure or limit the extent of free rotation of the cam 9, and hence the extent of rotation of the marking wheel. The block 15 has an upwardly-extending arm 19 thereon. Near the top of this arm is an adjusting screw 20, this screw sloping toward the cam wheel 9 in a position such that its forward end can contact a limit pin 21 projecting radially from the cam 9 to limit the rotational movement of the cam in a counterclockwise direction as viewed in FIGS. 2 and 3. By adjusting the screw 20 in the arm 19, the exact position at which such rotation will stop can be accurately predetermined.

Positioned against the block 15 is another block or bar 22. There is a tension spring 23 extending along the top edge of this bar having its rear end anchored through screw 24 to the rear end of the bar. Its forward end extends beyond the member 22 into the groove of wheel 8, and is attached to a pin or stud 25 carried in the groove of this wheel. Rotation of the marking die in a clockwise direction as viewed in FIG. 2 rotates the grooved wheel 8, and rotation of the grooved wheel stretches the spring 23, while the groove in the roller guides the spring. The spring will serve to rotate the parts in a counterclockwise direction.

When the marking wheel and shaft assembly rotates in a clockwise direction the spring is pulled around with the grooved wheel, being retained on its periphery by the groove. At the same time that the marking wheel and grooved wheel rotate, the cam 9 rotates, and its area of greatest radius moves against the end of the brake mem ber 16, pressing it in against the pressure of the spring 17. The friction of the brake against the eccentric with increasing pressure holds the rotatable assembly comprising the marking wheel, the eccentric and the grooved wheel against reverse rotation under the action of the tension spring 23.

To release the brake, the brake member 16 has a pin 26 projecting laterally therefrom through a slot 27 in the bar or block .22. There is an operating lever 28 pivoted at 29 to the side of bar 22, and its lower end is slotted to engage this pin 26. When the upper end of the lever is moved to the right as viewed in FIG. 1, the brake member is moved to the left against the compression of the spring 17, relieving the pressure against the eccentric cam 9,

thereby allowing spring 23 to rotate the parts to the normal starting position.

In a conventional screwmachine, the shank of the instrument is placed in a holder on the cross slide at one station of the machine so that the marking wheel may be moved by the operation of the machine radially toward and away from the axis of the work piece; 'The marking wheel is normally in the position shown in FIG. 1, but when it is advanced against the work piece, the relative rotation of the work piece and the tool holder causes the marking wheel to rotate against the surface of the work piece, and sufiicient pressure is applied to the roller by the inherent action of the machine to cause the marking characters to make their imprint on the work piece. The marking characters must engage the work piece during only one revolution of the work piece. Consequently, after the marking wheel has rotated far enough for the impression to be made in the work piece, the brake and eccentric cam prevent continued rotation in the same direction or any reverse rotation. When the tool holder or cross slide pulls back, the upper end of lever 28 strikes a stationary abutment on the screw machine (not shown) to retract the brake and release the rotatable marking assembly so that the parts return to starting position in readiness for the next cycle.

The marking wheel may be interchanged from time to time and very accurate determination of the starting position can be secured by the adjusting screw 20 and the limit pin or stop 21 on the cam. Thus the marking wheel rotates with the piece through an arc of less than 360 and cannot reverse until the tool is clear of the work piece. By adjusting the nut 18 the range of movement of the rotatable assembly may be increased or decreased. In the marking of a small piece, the marking wheel would .not be engaged with the work piece long enough to rotate it through an are as great as with a larger diameter work piece. Adjustment of the nut 18 enables the point to be selected at which the friction of the brake is suflicient to hold the rotatable assembly against continued rotation by engagement with the work piece or reverse rotation under the action of spring 23 until the brake is released. It may be explained that in the operation'of the tool the marking wheel must rotate far enough that the characters on the marking wheel entirely clear the work piece, and that if the spring 23 could be effective to immediately start the reverse rotation of the marking Wheel, the rotating work piece would be marred by the raised letters dragging on the work piece. On a small diameter work piece the inscription must be small, but with a larger diameter work piece, the characters at 12 may extend further around the periphery of the marking wheel to make a longer inscription. Adjustment of the friction brake will assure adequate travel of the marking wheel under any condition. If the marking wheel could be carried by its inertia through a full revolution, itwou-ld not only be likely to mar the work piece, but it would also foul the spring 23. The pin 21 is long enough so that it will either strike the brake or the yoke or head of the holder and form a positive step, thereby providing a safety factor if, for any reason, the brake is not properly set to check the rotation of the marking wheel assembly.

The device is simple in construction and may be readily adapted to various makes of screw machines. While intended primarily for use in screw machines, the device could be used in the tool holder of a lathe or in other environments where a mark is to be impressed in a work piece.

I have illustrated and described one specific embodiment of the invention, but it will be understood that various changes and modifications are contemplated within the scope of the appended claims.

I claim:

1. A marking tool of the class described comprising a holder, a rotatable marking wheel assembly in the holder having a marking wheel adapted to be rotated in one direction from a starting position by contact with a retating work piece, a spring for rotating the marking wheel assembly in the opposite direction to the starting position, an eccentric cam comprising part of said marking wheel assembly for rotation therewith, a brake member mounted in the holder for movement toward and away from said eccentric, biasing means resiliently urging the brake toward the eccentric, means for limiting the movement of the 'brake toward the eccentric, the brake and eccentric being so positioned that the brake is clear of the eccentric when the marking wheel assembly is in the starting position and being contacted by the eccentric after the marking wheel assembly has rotated a predetermined distance from the starting position, and a trip lever pivotally mounted on the holder and connected with the brake for moving the brake away from the e centric against the force of said biasing means.

2. A marking tool of the class described comprising a holder, a rotatable marking wheel assembly in the holder having a marking wheel adapted to be rotated in one direction from a starting position by contact with a rotating work piece, a spring for rotating the marking wheel assembly in the opposite direction to the starting position, an eccentric cam comprising part of said marking wheel assembly for rotation therewith, a brake member mounted in the holder for movement toward and away from said eccentric, biasing means resiliently urging the brake toward the eccentric, means for adjustably limiting the movement of the brake toward the accentric, the brake and eccentric being so positioned that the brake is clear of the eccentric when'the marking wheel assem bly is in the starting position and being contacted by the eccentric after the marking wheel assembly has rotated a predetermined distance from the starting position, and a trip lever pivotally mounted on the holder and connected with the brake for moving the brake away from the eccentric against the force of said biasing means.

3. A marking tool as defined in claim 2 where there is an adjustable stop on the holder and a stop-engaging member on the marking wheel assembly for predetermining the starting position of the wheel assembly.

References Cited in the file of this patent UNITED STATES PATENTS 460,058 Luehrs Sept. 22, 1891 2,408,516 Horton Oct, 1, 1946 2,610,576 Norris Sept. 16, 1952 2,974,583 Friedman Mar. 14, 1961 

